<!DOCTYPE html>
<html lang="zh_CN">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

</body>
<script type="text/javascript">

    /*1. 变量的声明 */
    var number1;
    var number2;
    var sum;

    /*2. 接收用户的输入信息*/
    number1 = window.prompt('输入一个数字：');
    number2 = window.prompt('再输入一个数字：');

    /*3. 类型的转换 */
    number1 = parseInt( number1 );
    number2 = parseInt( number2 );

    /*4. 求和*/
    sum = number1 + number2;

    /*5. 弹出*/
    alert( 'number1 + number2 = ' + sum); // 12 + 13 = 25;


</script>

</html>
